Fallback Between Radio Access Technologies

1. A method for assigning a location area to a mobile device in fallback from a first radio access network to a second radio access network, the location area being selected from a plurality of location areas, each corresponding to a separate location area code (LAC), the first radio access network comprising a base station node having a respective first counter corresponding to each LAC, the method comprising: receiving, by the base station node, a signal incorporating one of the LACs and further identifying data corresponding to the second radio access network; comparing the first counter corresponding to the one LAC with a predefined threshold value and if the first counter corresponding to the one LAC is less than the predefined threshold value, incrementing the first counter corresponding to the one LAC, otherwise incrementing a second counter corresponding to a unique combination of the one LAC and the further identifying data; and reporting, at a predetermined interval, the count from the second counter to the first radio access network.

2. The method recited in claim 1 , wherein the first radio access network is a Long-Term Evolution (LTE) network and the second radio access network is a GSM/EDGE Radio Access Network (GERAN).

3. The method recited in claim 1 , wherein the first radio access network is an LTE network and the second radio access network is a Universal Terrestrial Radio Access Network (UTRAN).

4. The method recited in claim 1 , further comprising providing the second counter before incrementing the second counter if the second counter does not exist.

5. A base station node arranged to implement the method recited in claim 1 .

6. The method recited in claim 1 , wherein the predefined threshold value is one of 64, 100, 127, and 255.

7. A method for assigning location areas to mobile devices in fallback from a first radio access network to a second radio access network, the location areas being selected from a plurality of location areas, each corresponding to a separate location area code (LAC), the first radio access network comprising a base station node having a respective first counter corresponding to each LAC, the method comprising: receiving, by the base station node, a plurality of signals, each incorporating one of the LACs and further identifying data corresponding to the second radio access network; for each received signal, comparing the first counter corresponding to the LAC of the received signal with a predefined threshold value and if the first counter is less than the predefined threshold value, incrementing the first counter, otherwise incrementing a second counter corresponding to a unique combination of the LAC of the received signal and the further identifying data; and reporting, at a predetermined interval, the count from the second counters to the first radio access network.

8. The method recited in claim 7 , further comprising, for each received signal, providing the second counter before incrementing the second counter if the second counter does not exist.

9. The method recited in claim 7 , wherein reporting the count from the second counters to the first radio access network comprises reporting a subset of the second counters to the first radio access network, the subset representing the second counters having the highest counts over the reporting period.

10. The method recited in claim 7 , wherein the predefined threshold value is one of 64, 100, 127, and 255.

11. A base station node arranged to implement the method recited in claim 7 .

12. A base station node comprising: a plurality of first counters, each corresponding to a separate location area code (LAC); one or more second counters, each corresponding to a unique combination of one of the LACs and further identifying data corresponding to a radio access network, the first and second counters being configured to be used as follows: whenever the base station node receives a signal incorporating a LAC and further identifying data, the first counter corresponding to the LAC is compared to a predefined threshold value and if the first counter corresponding to the LAC is less than the predefined threshold value, the first counter is incremented, otherwise, the second counter corresponding to the unique combination of the LAC and the further identifying data is incremented; at a predetermined interval, the count from the second counters are reported to the radio access network.

13. The base station node recited in claim 12 , wherein each of the second counters is created after the first counter corresponding to the corresponding LAC has reached the predefined threshold value.

14. The method recited in claim 12 , wherein the predefined threshold value is one of 64, 100, 127, and 255.